Gyratory crushers are used for crushing ore, mineral and rock material to smaller sizes. Typically, the crusher comprises a crushing head mounted upon an elongate main shaft. A first crushing shell is mounted on the crushing head and a second crushing shell is mounted on a frame such that the first and second crushing shells define together a crushing gap through which the material to be crushed is passed. A driving device is arranged to rotate an eccentric assembly about the lower portion of the shaft so as to cause the crushing head to perform a gyratory pendulum movement and crush the material introduced in the crushing gap.
Typically, the main shaft is mounted at its upper end by a top bearing assembly in turn mounted within a spider. The main shaft and internal region of the spider are protected from wear via a sleeve that is typically friction fitted over the upper end of the main shaft and a floating spider bushing that protects the inward facing surface of the spider. Conventional sleeve and bushing assemblies are described in U.S. Pat. Nos. 1,110,887; 1,748,102; 2,598,548; 4,060,205 and WO 2011/139210.
Typically, the spider bushing is manufactured from grey iron which facilitates manufacture and is low cost. However, existing bushings are disadvantageous as they exhibit relatively low wear resistance and require frequent replacement. Accordingly, what is required is a spider bushing that addresses these problems.